This application relates to a novel inhibitor of angiogenesis useful for treating angiogenesis-related diseases, such as angiogenesis-dependent cancer. The invention further relates to a novel composition and method for curing angiogenesis-dependent cancer. In addition, the present invention relates to diagnostic assays and kits for endostatin measurement, to histochemical kits for localization of endostatin, to molecular probes to monitor endostatin biosynthesis, to antibodies that are specific for the endostatin, to the development of peptide agonists and antagonists to the endostatin receptor, and to cytotoxic agents linked to endostatin peptides.
Several lines of direct evidence now suggest that angiogenesis is essential for the growth and persistence of solid tumors and their metastases (Folkman, 1989; Hori et al., 1991; Kim et al., 1993; Millauer et al., 1994). To stimulate angiogenesis, tumors upregulate their production of a variety of angiogenic factors, including the fibroblast growth factors (FGF and BFGF) (Kandel et al., 1991) and vascular endothelial cell growth factor/vascular permeability factor (VEGF/VPF). However, many malignant tumors also generate inhibitors of angiogenesis, including angiostatin and thrombospondin (Chen et al., 1995; Good et al., 1990; O""Reilly et al., 1994). It is postulated that the angiogenic phenotype is the result of a net balance between these positive and negative regulators of neovascularization (Good et al., 1990; O""Reilly et al., 1994; Parangi et al., 1996; Rastinejad et al., 1989). Several other endogenous inhibitors of angiogenesis have been identified, although not all are associated with the presence of a tumor. These include, platelet factor 4 (Gupta et al., 1995; Maione et al., 1990), interferon-alpha, interferon-inducible protein 10 (Angiolillo et al., 1995; Strieter et al., 1995), which is induced by interleukin-12 and/or interferon-gamma (Voest et al., 1995), gro-beta (Cao et al., 1995), and the 16 kDa N-terminal fragment of prolactin (Clapp et al., 1993). The only known angiogenesis inhibitor which specifically inhibits endothelial cell proliferation is angiostatin (O""Reilly et al. 1994).
Angiostatin is an approximately 38 kiloDalton (kDa) specific inhibitor of endothelial cell proliferation. Angiostatin is an internal fragment of plasminogen containing at least three of the five kringles of plasminogen Angiostatin has been shown to reduce tumor weight and to inhibit metastasis in certain tumor models. (O""Reilly et al., 1994). As it is used hereinafter, the term xe2x80x9cangiostatinxe2x80x9d refers to angiostatin as described above; peptide fragments of angiostatin that have endothelial cell proliferation inhibiting activity; and analogs of angiostatin that have substantial sequence homology (as deemed herein) to the amino acid sequence of angiostatin, which have endothelial cell proliferation inhibiting activity.
The present invention relates to a novel protein inhibitor, and method for its use. The protein is a potent and specific inhibitor of endothelial proliferation and angiogenesis. Systemic therapy with the inhibitor causes a nearly complete suppression of tumor-induced angiogenesis, and it exhibits strong anti-tumor activity.
The inhibitory protein has a molecular weight of approximately 18,000 to approximately 20,000 Daltons (18 to 20 kDa) and is capable of inhibiting endothelial cell proliferation in cultured endothelial cells. The protein can be further characterized by its preferred N-terminal amino acid sequence, the first twenty (20) of which are as follows:
A preferred endothelial cell proliferation inhibitor of the invention is a protein having the above-described characteristics, and which can be isolated and purified from the murine hemangioendothelioma cell line EOMA. This inhibitory protein has been named endostatin.
The present invention provides methods and compositions for treating diseases and processes mediated by undesired and uncontrolled angiogenesis by administering to a human or animal with the undesired angiogenesis a composition comprising a substantially purified endostatin or endostatin derivative in a dosage sufficient to inhibit angiogenesis. The present invention is particularly useful for treating or for repressing the growth of tumors. Administration of endostatin to a human or animal with prevascularized metastasized tumors prevents the growth or expansion of those tumors.
The present invention also includes diagnostic methods and kits for detection and measurement of endostatin in biological fluids and tissues, and for localization of endostatin in tissues. The diagnostic method and kit can be in any configuration well known to those of ordinary skill in the art. The present invention also includes antibodies specific for the endostatin and antibodies that inhibit the binding of antibodies specific for the endostatin. These antibodies can be polyclonal antibodies or monoclonal antibodies. The antibodies specific for endostatin can be used in diagnostic kits to detect the presence and quantity of endostatin which is diagnostic or prognostic for the occurrence or recurrence of cancer or other diseases mediated by angiogenesis. Antibodies specific for endostatin may also be administered to a human or animal to passively immunize the human or animal against endostatin, thereby reducing angiogenic inhibition.
The present invention also includes diagnostic methods and kits for detecting the presence and quantity of antibodies that bind endostatin in body fluids. The diagnostic method and kit can be in any configuration well known to those of ordinary skill in the art.
The present invention also includes endostatin peptide fragments that can be labeled isotopically or with other molecules or proteins for use in the detection and visualization of endostatin binding sites with state of the art techniques, including, but not limited to, positron emission tomography, autoradiography, flow cytometry, radioreceptor binding assays, and immunohistochemistry.
These endostatin peptides also act as agonists and antagonists at the endostatin receptor, thereby enhancing or blocking the biological activity of endostatin. Such peptides are used in the isolation of the endostatin receptor.
The present invention also includes endostatin, endostatin fragments, endostatin antisera, or endostatin receptor agonists and antagonists linked to cytotoxic agents for therapeutic and research applications.
The present invention includes molecular probes for the ribonucleic acid and deoxyribonucleic acid involved in transcription and translation of endostatin. These molecular probes provide means to detect and measure endostatin biosynthesis in tissues and cells.
A surprising discovery is that various forms of recombinant endostatin protein can serve as sustained release anti-angiogenesis compounds when administered to a tumor-bearing animal. A preferred form of the sustained release compound is un-refolded recombinantly produced endostatin.
Additionally, the present invention encompasses nucleic acid sequences comprising corresponding nucleotide codons that code for the above disclosed amino acid sequence and for endostatin and endothelial cell proliferation inhibiting peptide fragments thereof.
The present invention also relates to methods of using the endostatin protein and peptide fragments, corresponding nucleic acid sequences, and antibodies that bind specifically to the inhibitor and its peptides, to diagnose endothelial cell-related diseases and disorders.
The invention further encompasses a method for identifying receptors specific for endostatin, and the receptor molecules identified and isolated thereby.
The invention also relates to a method for identifying novel enzymes capable of releasing endostatin from collagen type XVIII, and other molecules containing an endostatin amino acid sequence, and peptides thereof. Such endostatin producing enzymes are also an aspect of the invention.
An important medical method is a new form of birth control, wherein an effective amount of endostatin is administered to a female such that uterine endometrial vascularization is inhibited and embryo implantation cannot occur, or be sustained.
A particularly important aspect of the present invention is the discovery of a novel and effective method for treating angiogenesis-related diseases, particularly angiogenesis-dependent cancer, in patients, and for curing angiogenesis-dependent cancer in patients. The method unexpectedly provides the medically important result of inhibition of tumor growth and reduction of tumor mass. The method relates to the co-administration of the endostatin of the present invention and another anti-angiogenesis compound, preferrably angiostatin. Accordingly, the present invention also includes formulations containing endostatin, and optionally angiostatin, which are effective for treating or curing angiogenesis-dependent cancers.
Accordingly, it is an object of the present invention to provide a composition comprising an endostatin protein.
It is another object of the present invention to provide a method of treating diseases and processes that are mediated by angiogenesis.
It is yet another object of the present invention to provide a diagnostic or prognostic method and kit for detecting the presence and amount of endostatin in a body fluid or tissue.
It is yet another object of the present invention to provide a method and composition for treating diseases and processes that are mediated by angiogenesis including, but not limited to, hemangioma, solid tumors, leukemia, metastasis, telangiectasia psoriasis scleroderma, pyogenic granuloma, myocardial angiogenesis, plaque neovascularization, corornay collaterals, cerebral collaterals, arteriovenous malformations, ischemic limb angiogenesis, corneal diseases, rubeosis, neovascular glaucoma, diabetic retinopathy, retrolental fibroplasia, arthritis, diabetic neovascularization, macular degeneration, wound healing, peptic ulcer, fractures, keloids, vasculogenesis, hematopoiesis, ovulation, menstruation, and placentation.
It is another object of the present invention to provide a composition for treating or repressing the growth of a cancer.
It is an object of present invention to provide a method for detecting and quantifying the presence of an antibody specific for an endostatin in a body fluid.
Still another object of the present invention is to provide a composition consisting of antibodies to endostatin that are selective for specific regions of the endostatin molecule.
It is another object of the present invention to provide a method for the detection or prognosis of cancer.
It is another object of the present invention to provide a composition for use in visualizing and quantitating sites of endostatin binding in vivo and in vitro.
It is yet another object of the present invention to provide a composition for use in detection and quantification of endostatin biosynthesis.
It is yet another object of the present invention to provide a therapy for cancer that has minimal side effects.
Still another object of the present invention is to provide a composition comprising endostatin or an endostatin peptide linked to a cytotoxic agent for treating or repressing the growth of a cancer.
These and other objects, features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims.